Results 1 to 5 of 5
  1. #1
    New Member
    Join Date
    Mar 2008
    Location
    Florida
    Posts
    6

    Building New Cable plant - Cable suggestions

    As I'm setting to build a new cable plant both audio and video. I love this part of my job. I'd like to open a discussion about the audio cables you folks can recommend. I'm going to a 66 ohm Z inputs on the router from mostly balanced sources and destinations with some converted unbalanced sources. I'll convert with the MM100 matchmakers that can adjust. I'm considering the 1800F cable but it's not specifically for line level audio but has low C. It's 110 ohm though and some loss is likely evident. Or.. the Belden 1883 which is made specifically for line levels but may be a lot less flexible. I'll be spreading this across 7 or 8 19" equipment racks.

    What say you?

    YoJo

  2. #2
    Senior Member SC358's Avatar
    Join Date
    May 2005
    Location
    NYC
    Posts
    608
    Blog Entries
    2
    Hey YoJo-

    Since you opened this discussion, Iím assuming that youíre in the planning stages for at least the next few weeks, I donít know - at least you have the time to explore for yourself. Hereís something that is somewhat on the radical side.

    Iíve had read a white paper, seen a demo and had discussions with Belden about, Non-Data Applications for Category 5 Cable http://www.belden.com/pdfs/Techpprs/ndac5ctp.htm

    This is about using Category 5, 5E or 6 (UTP-Unshielded Twisted Pairs) in replacement of audio cables (whether twisted pairs or co-ax). In short, Cat 5 cable (and higher) exceeds the technical requirements of standard and long used audio cable. Most engineers usually worry about hum induced via the cables, with some relief knowing that as long as the cable is grounded on one side, there should be no problem. When in fact it is the balance circuitry thatís suppose to be rejecting it.

    In addition, Cat 5 is inexpensive compared to other 1000í audio cables. Donít forget, each pull gives you 4 twisted pairs.

    You may be wondering if this has been done. Yes it has with satisfying results from what I have heard. I have yet to get my tour of a particular radio station who has done this.

    I highly suggest reading the above link to give you a better understanding and opening more discussions.
    SC358
    Relationships are based on compromises - behavior accepted is behavior repeated.

  3. #3
    New Member
    Join Date
    Mar 2008
    Location
    Florida
    Posts
    6

    Intriguing but...

    I won't be allowed to pull something like that off. If this weren't a gvt contracted revamp, I would surely run some lines to analyze. I was more interested in traditional approaches and was feeling some risk in using this 110 Z mic cable (1800F) vs. some stiff foiled wire that feels like junk to me in comparison. I am running out of time though. My weeks of planning time is gone and it's time to buy. Am I off base thinking that the Z missmatch won't impede (pardon the pun) the signal quality at all on a 30ft run?

  4. #4

    Much Ado About Nothing

    This is a non-issue, especially at 30 feet. Cable characteristics have to do with transmission line behavior. A cable is a transmission line only if it is at least 1/10th as long as the highest frequency it will be required to carry. If we take the highest audio frequency as 20kHz, that's in the neighborhood of a mile.

    When the cable is very short compared to the wavelength, there's no such thing as wave behavior on it, so it isn't a transmission line. It's just a wire with voltage on it. In which case the characteristic impedance of the cable itself doesn't matter.

    Cable with foil shield has been the standard studio wiring stuff for many years. Cut the foil shields off and connect the drain wires that contact them to ground. Of course, this kind of cable is for permanent installation. It's not to be used for mic cords that will be flexed and moved around.

    BTW, the studios of Minnesota Public Radio (which you know as Public Radio International) were once wired with unshielded multipair telephone cable, which is about CAT1. Works fine as long as everything is well balanced - that means floating transformer isolation.

  5. #5
    New Member
    Join Date
    Mar 2008
    Location
    Florida
    Posts
    6

    You folks are right - I'm just being nervous

    I went ahead and bought the Belden 1800F Mic cable. Yea it's a bit more expensive but it's very flexible, feels great, Has a great rep., and is plain impressive. I can use any excess for other applications as well.

    Thanks guys for calming me!
    Moe, Larry, the cheese!

    YoJo

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Subscribe to us on YouTube